The invention relates to a fluid actuating device for an electric circuit breaker, in particular a high-voltage power circuit breaker. The actuating device includes an actuator consisting of a differential piston and a cylinder. The differential piston is continuously exposed to the pressure of the pressure fluid on its small-area end-face and selectively, by means of a valve arrangement, on the large-area end-face.
A fluid actuating device of the foregoing type is disclosed, for example, in the copending U.S. patent application of Gerhard Grieger and Joaquin Bohrdt entitled: FLUID ACTUATING DEVICE FOR AN ELECTRIC CIRCUIT BREAKER.
Fluid actuating devices for electric circuit breakers, and in particular, for high-voltage power circuit breakers, must fulfill the purpose of moving the movable contacts as fast as possible and without delay in dependence on the control command for closing or opening the breaker. As for moving the movable contacts of modern, high-speed high-voltage power circuit breakers, which weigh several kilograms, an energy of several meter-kilograms is required for the drive, the differential pistons of fluid actuating devices must be transferred from their one end-position to the other end-position with considerable acceleration. To prevent rebound caused by impact, the piston motion must be decelerated in a suitable manner over a short stroke.